The profile of phase or amplitude diffraction grating plays a dominant role for achieving the ultimate efficiency of the photonic devices. Recent laser-beam and e-beam writing techniques allow desired profile patterning in contrast to the holographic recording, which tends to produce symmetrical sinusoidal grooves. As the diffraction efficiency (DE) is highly dependent on the grating profile shape and depth this requires much better detailed quantitative knowledge on the influence of the real profile on the grating performance.  To this aim we present a new method for DE analyses for transmission phase and amplitude gratings with arbitrary profile and depth. A comparative study of the grating efficiency for different groove profiles (sinusoidal, rectangular, triangular, cycloidal and blazed) was performed by modeling of diffraction process on gratings using Angular Spectrum method in Matlab software. It allowed to simulate the propagation of a wavefront through desired diffraction structures and to observe the form and intensity of the wavefront in the output plane. It was assumed that the grating period Λ was equal to 1 μm and monochromatic light at wavelength λ=650 nm was incident in a plane perpendicular to the grating vector (classical diffraction mount). The modulation depth of amplitude and phase gratings ΔT and Δφ was varied from 0 to 1 (transmission change from 0% to 100%) and from 0 to 2π rad correspondingly. It can be recalculated into refractive index modulation Δn or surface relief depth Δd using next expressions: and .  The DE for the amplitude and phase gratings with different groove profiles is presented in Fig. 1 and 2 correspondingly. Maximum achievable DE for different profile shape is presented for every type of gratings in dependence on ΔT (Fig. 1) and on Δφ and Δd (Fig. 2). Surface relief depth Δd was recalculated from Δ φ for λ=650 nm and n=2.5. It is shown that the diffraction efficiency is much more for phase gratings, and phase blazed profile has the ―best‖ performance with the highest diffraction efficiency up to 100%. A good agreement between obtained maximum values of DE and known ones for conventional sinusoidal and rectangular profiles of gratings confirms reliability of proposed approach. It provides an useful method to predict the DE of amplitude and phase grating with arbitrary profile.